Olmsted County population aged ≥50 years; data adjusted for applicability to overall US white population

8.8 (narrow) 17.4 (broad)

Age-adjusted, sex-adjusted

Ehrlich [15]

2010

CA, USA

1996–2005

Health insurance plan database

IPFPF

ICD-9 516.3/515

Health plan population; data adjusted for applicability to overall US population aged ≥18 years

9 (non-diabetics) 14 (diabetics)

Crude Age-adjusted, by diabetic status

Raghu [16]

2006

USA

1996–2000

Health claims database

IPF

ICD-9 516.3

Health claims database population; data adjusted for applicability to overall US population

16.3 (broad) 6.8 (narrow)

Age-adjusted

South America

Rufino [17]¶

2013

Brazil

1996–2010

Ministry of Health data

IPF

ICD-10 J84.1

0.48

Crude

Asia

Han [18]¶

2013

South Korea

1992–2010

Healthcare claims from insurance medical cohort

IPF

NA

NA

4.16 (broad) 1.84 (narrow)

Crude, patients >30 years

Lai [19]

2012

Taiwan

1997–2007

Health insurance database/ government records

IPF

ICD-9 516.3

Population of the Taiwan National Health Insurance database

1.4 (broad) 1.2 (narrow)

Crude

Natsuizaka [20]

2014

Hokkaido prefecture, Japan

2003–2007

Ministry of Health, Labor and Welfare data

IPF

ATS/ERS consensus classification

Overall population of Hokkaido

2.23

Crude

International Classification of Diseases (ICD) codes are presented as ICD-nth revision, clinical modification (CM). ICD-10 code J84.1 is currently the most specific code for IPF but may include other idiopathic interstitial pneumonia (IIP). ICD-9 code 516.3 is roughly equivalent; code 515 is “post-inflammatory fibrosis”. Broad criteria were: one or more claims with a diagnostic code for IPF, but no claims for another diagnostic code for interstitial lung disease (ILD). Narrow criteria were: as for broad criteria, with a relevant diagnostic test on or before their first diagnosis date. Broad and narrow criteria were based on the 2002 American Thoracic Society (ATS)/European Respiratory Society (ERS) guidelines [21]. Probable cases were based on criteria from [22]: received a diagnosis of ILD from a rheumatologist or pulmonary physician; or ILD was the primary discharge diagnosis. Definite cases had a confirmatory diagnosis within 90 days. CPRD: Clinical Practice Research Datalink; NA: not available; THIN: The Health Improvement Network; IFA: idiopathic fibrosing alveolitis; PF: pulmonary fibrosis; CFA: cryptogenic fibrosing alveolitis; PPV: positive-predictive value; IIP: idiopathic interstitial pneumonia; IPF: idiopathic pulmonary fibrosis. #: average incidence for the time period available; latest incidence stated where no average was given, incidence extrapolated from ILD data where percentage of IPF cases was given; ¶: abstract only. Reproduced and modified from [23] with permission.